Depletion of fuel cells has brought about a great increase in price of energy sources and increased interest in environmental pollution. Eco-friendly alternative energy sources are a necessity for the next generation. In this regard, a great deal of research into power production methods such as nuclear energy, sunlight, wind power and tidal power is underway and power storage devices for efficiently utilizing the produced energy also attract much attention.
In particular, regarding lithium secondary batteries, an increase in technological development and demand associated with mobile equipment has led to a sharp increase in demand for lithium secondary batteries as energy sources. Recently, use of lithium secondary batteries as power sources of electric vehicles (EVs) and hybrid electric vehicles (HEVs) has become popularized and usage thereof is expanding to applications such as auxiliary power supply through grid-realization.
An anode of a conventional lithium secondary battery generally utilizes a carbon-based compound which enables reversible intercalation and deintercalation of lithium ions while maintaining structural and electric properties as an anode active material. On the other hand, recently, rather than conventional carbon-based anode materials, a great deal of research associated with anode materials obtained through lithium alloy reaction using silicon (Si) and tin (Sn), and lithium titanium oxides is underway.
Lithium titanium oxide (Li4Ti5O12) is known as a zero-strain material that suffers minimal structural deformation during charge/discharge, exhibits considerably superior lifespan, does not cause generation of dendrites and has considerably superior safety and stability. In addition, lithium titanium oxide electrodes are greatly advantageous as they can be quickly charged within several minutes.
Lithium titanium oxide has disadvantages of high potential and low capacity, as compared to conventional carbon-based anode materials.
Silicon- and tin-based metal materials are known to have high capacity, but disadvantageously exhibit great variation in volume when reacting with lithium.